Well-wishers have turned the route of the royal wedding procession into a sea of red, white and blue as the world came together to celebrate Prince William and Kate Middleton's big day.
Waving flags and clutching umbrellas against the predicted rain, the crowds waited with mounting excitement for the first glimpse of the couple - and in particular the bride's dress, which has been kept a closely-guarded secret.
Kate was said to be nervous but calm as she made her final preparations for a ceremony that will be watched on television by two billion people worldwide.
The Dean of Westminster, the Very Rev Dr John Hall, who is conducting the service, told Sky News: "I think she will be quite calm, as a matter of fact.
"She seems to be very much in control of herself and looking forward very much to the day.
"After the final rehearsal when William and Catherine came on Wednesday evening, they both seemed to be very happy. I'm sure they will be a little bit nervous but I'm sure they can cope with that."
Among the 1,900 guests invited to the Westminster Abbey service are a number of celebrities, including David and Victoria Beckham.
Victoria spoke of her delight at the occasion, writing on Twitter: "London looks beautiful!!! We are so proud to be British!"